Heat-resistant styrene copolymer and styrene resin composition comprising the same

Abstract

Provided is a styrene resin composition including α-methyl styrene, acrylonitrile and vinyl imidazole, and having an improved conversion rate while maintaining excellent mechanical and chemical properties, a styrene resin composition including the same, and a styrene resin molded product manufactured therefrom. Accordingly, the heat-resistant styrene copolymer is effective in improving a conversion rate without deformation and mechanical and chemical property decline of the material itself, and as a result, commercialization may be readily accomplished due to enhanced productivity. In addition, the styrene resin molded product manufactured from the styrene resin composition according to the present invention includes the heat-resistant styrene copolymer as a matrix copolymer, and therefore, has excellent impact strength, tensile strength, tensile elongation and flowability while having high heat resistance.

The invention claimed is: 
     
       1. A heat-resistant styrene copolymer comprising:
 A) α-methyl styrene in an amount of 60 wt % to 78 wt %; 
 B) acrylonitrile in an amount of 20 wt % to 38 wt %; and 
 C) vinyl imidazole in an amount of 0.5 wt % to 7 wt %, 
 wherein the styrene copolymer has, when polymerized at a polymerization temperature of 105° C., a conversion rate of 40% to 60%, a glass transition temperature (Tg) in a range of 123° C. to 128° C., and a weight average molecular weight (Mw) of 87,000 to 90,000, and 
 wherein the A) α-methyl styrene, the B) acrylonitrile and the C) vinyl imidazole have a weight ratio of 70:25 to 27:3 to 5. 
 
     
     
       2. A styrene resin composition comprising:
 an a) heat-resistant styrene copolymer in an amount of 60 wt % to 80 wt %; and 
 a b) rubber copolymer in an amount of 20 wt % to 40 wt %, 
 wherein the a) heat-resistant styrene copolymer includes A) α-methyl styrene in an amount of 60 wt % to 78 wt %, B) acrylonitrile in an amount of 20 wt % to 38 wt %, and C) vinyl imidazole in an amount of 0.5 wt % to 7 wt %, and 
 wherein the b) rubber copolymer is at least one selected from the group consisting of an acrylonitrile-butadiene-styrene (ABS) graft copolymer having a core-shell structure and an acrylate-styrene-acrylonitrile (ASA) graft copolymer having a core-shell structure. 
 
     
     
       3. The styrene resin composition of  claim 2 , wherein the b) rubber copolymer has an average diameter of 250 nm to 500 nm. 
     
     
       4. The styrene resin composition of  claim 2 , wherein the acrylonitrile-butadiene-styrene graft copolymer has a core-shell structure (ABS) comprising a diene copolymer core in 50 wt % to 80 wt %; and a shell including a first monomer and a second monomer grafted on the core in 20 wt % to 50 wt %, and
 wherein a thickness ratio of the core to the shell is from 4:6 to 8:2, 
 wherein the first monomer is at least one selected from the group consisting of styrene, α-methyl styrene, α-ethyl styrene, p-ethyl styrene, and vinyl toluene, and 
 wherein the second monomer is at least one selected from the group consisting of acrylonitrile, methacrylonitrile, and ethacrylonitrile. 
 
     
     
       5. The styrene resin composition of  claim 4 , wherein the shell comprises the first monomer and the second monomer in a weight ratio of 7:3 to 8:2. 
     
     
       6. The styrene resin composition of  claim 4 , wherein the diene copolymer is derived from one or more of conjugated diene monomers selected from the group consisting of 1,3-butadiene, isoprene, chloroprene and piperylene. 
     
     
       7. The styrene resin composition of  claim 2 , wherein the acrylate-styrene-acrylonitrile graft copolymer has a core-shell structure (ASA) comprising an acrylate polymer core in an amount of 40 wt % to 60 wt %; and a shell including a first monomer and a second monomer grafted on the core in an amount of 40 wt % to 60 wt %,
 wherein a thickness ratio of the core to the shell is from 4:6 to 8:2, 
 wherein the first monomer is at least one selected from the group consisting of styrene, α-methyl styrene, α-ethyl styrene, p-ethyl styrene, and vinyl toluene, and 
 wherein the second monomer is at least one selected from the group consisting of acrylonitrile, methacrylonitrile, and ethacrylonitrile. 
 
     
     
       8. The styrene resin composition of  claim 7 , wherein the shell includes the first monomer and the second monomer in a weight ratio of 7:3 to 8:2. 
     
     
       9. The styrene resin composition of  claim 7 , wherein the acrylate polymer is derived from butyl acrylate, ethylhexyl acrylate or a mixture thereof. 
     
     
       10. The styrene resin composition of  claim 2 , wherein the styrene resin composition further comprises one or more additives selected from the group consisting of a thermal stabilizer, a lubricant, an antioxidant, a photostabilizer, a flame retardant, an antistatic agent, a coloring agent, a filler and a UV stabilizer. 
     
     
       11. A styrene resin molded product manufactured from the styrene resin composition of  claim 2 . 
     
     
       12. The styrene resin molded product of  claim 11 , which has impact strength of 20 J/m to 25 J/m measured in accordance with ASTM D256 when having a thickness of ¼″, and has tensile elongation of 23% to 40% measured in accordance with ASTM D638 under a rate condition of 5 cm/min when having a thickness of ⅛″.